On Mon, Apr 29, 2019 at 12:13 PM Linus Torvalds torvalds@linux-foundation.org wrote:
On Mon, Apr 29, 2019, 12:02 Linus Torvalds torvalds@linux-foundation.org wrote:
If nmi were to break it, it would be a cpu bug.
Side note: we *already* depend on sti shadow working in other parts of the kernel, namely sti->iret.
Where? STI; IRET would be nuts.
Before:
commit 4214a16b02971c60960afd675d03544e109e0d75 Author: Andy Lutomirski luto@kernel.org Date: Thu Apr 2 17:12:12 2015 -0700
x86/asm/entry/64/compat: Use SYSRETL to return from compat mode SYSENTER
we did sti; sysxit, but, when we discussed this, I don't recall anyone speaking up in favor of the safely of the old code.
Not to mention that the crash we'll get if we get an NMI and a rescheduling interrupt in this path will be very, very hard to debug.